From the Northern Border--reported fighting on the Potomac.
In the absence of any official or authentic information with reference to the operations of the Army of the Potomac, we have an abundance of rumors, some of which are perhaps well founded and entitled to consideration. The last report we have of the forward movement of our forces is, that the corps of Gen. Longstreet crossed the Potomac at Edwards's Ferry, near Leesburg, on Sunday morning, and that splendid body of soldiers now occupy the neutral territory of Maryland. It is stated, in connection with this report, that a pretty severe fight took place on Saturday, previous to crossing, between the rear guard of Longstreet's corps and the advance of the enemy in the neighborhood of Leesburg. We are inclined to think, however, from the best information we have upon the subject, that all the fighting that has occurred has been between the cavalry forces of the contending armies. It is hardly to be supposed that if Gen. Longstreet had been actively engaged in battle on Saturday, with his rear closely pressed by Hooker's forces, he would have continued his advance and crossed the river on Sunday morning.We think it altogether likely that the report of a heavy engagement has originated in the series of brilliant fights which General Stuart has had with the enemy, in all which we have every reason to believe he has been more than usually successful. With reference to these fights, and the condition of our army, we give the following extract from a letter written by a member of the 10th Virginia cavalry to a friend in this city, and dated on Saturday last. The writer says:
‘ "Since Thursday we have been constantly skirmishing with the enemy — always successfully. We have taken numbers of prisoners and horses. The latter do us much the most good every way.
’ "I hardly know whether you would enjoy it or not, but I wish you could see Gen. Lee's noble army in motion, and I have within a few days past. Never was there a more finely organized body of men in the world. The men are all in splendid spirits. There is no straggling."
